Apparatus for smelting metals, steels, and alloys thereof or other hard melting materials



J1me 1960 A. LINDNER APPARATUS FOR SMEL'IING METALS, STEELS. AND ALLOYS THEREOF OR OTHER HARD MEL-TING MATERIALS Filed Oct. 3, 1957 2 Sheets-Sheet 1 Fig. 1

l J a K is L 12 //VV[/V7'0/Q June 28, 1960 A. LINDNER 2,943,130

APPARATUS FOR SMEJLTING METALS, STEELS. AND ALLOYS THEREOF OR OTHER HARD MELTING MATERIALS Filed Oct. 3, 1957 2 Sheets-Sheet 2 United States Patent APPARATUS FOR SMELTING METALS, STEELS, AND ALLOYS THEREOF OR OTHER HARD MELTING MATERIALS Arno Lindner, Diefenbachstrasse 11, Munich-Sella, Germany Filed on. a, 1951, Set; No. 687,896 4 Claims. (Cl.13-22) The invention relates to apparatus for melting metals, metal alloys, steels, steel alloys or other materials which it is diificult to melt, such as silicates.

More in particular, the invention relates to a melting apparatus of this type in which an electrically heated crucible or a tube surrounding the crucible is connected between current carrying contacts. The current carrying contacts are preferably connected to the secondary ofa transformer.

Apparatuses of this type are known, particularly for melting gold, silver, platinum, metal alloys and steel alloys having a high melting point, such as, for example, chromium nickel steel alloys, silicates or other materials which it is ditficult to melt. While for melting materials which have a low melting point a carbon or graphite crucible is employed, which is connected directly between the contacts, it is advantageous in melting materials above 1500 C. as, for example, in the temperature range between 2000 and 3000 C., to permit the contacts at both ends to engage the end surfaces of a carbon tube or to connect a special crucible of a highly refractory or heat resistant ceramic material, such 'as eorundum or magnesium oxide inside the tube, the material characteristics of which may be adapted to the substance being melted, so that chemical eifects of the material of the crucible on the substance are avoided. One of the problems involved in that type of construction is that the high heat to which the apparatus is subjected causes uneven expansion and, therefore, cracking or breakage of components.

It is, therefore, one object of the invention to provide a melting apparatus of theaforementioned type which is adapted to avoid damage or breakage resulting from expansion during heating to the crucible or to the tube in which the crucible is mounted.

It is a further object of the invention touavoid onesided or local overheating of the places of contact between the crucible and the contacts or the carbon tube and the contactswhich could result in trouble during the heating and couldalso cause burn outs at the end surfaces of the crucible or of thecarbon tube.

The invention generally provides an apparatus for melting metals, metal alloys oriother substances and steels or steel alloys which it is diiiicultv to melt, in which an electrically heated crucible or' a tube surrounding the crucible is connected as a resistor between current carrying contacts and provides more in particular .that the crucible or the tube is resiliently and elastically connected to the contacts which engage the transverse ends thereof.

It is still a further object of the invention, to provide, a melting apparatus of the aforementioned type in which at least the contacts on one transverse end of the crucible or tube are arranged to be movable in a direction axially of the crucible or tube. Y

It is furthermore an object of the invention to provide such a melting apparatus in which'the contacts comprise I ice head by means of two spindles with the crucible or tube connected therebetween, while the spindles are adjustable against the pressure of the springs disposed inside of tubes to which the lower contact head is rigidly secured.

It is still an additional object of the invention to guide the upper contact head in such a manner on the two spindles that it can assume'a certain oblique position with respect to the longitudinal axes of the spindles. Thus, in accordance with the invention the guidance of the upper contact head can be so arranged with respect to the spindles that it can place itself obliquely in different directions with respect to the spindles.

In accordance with one embodiment of the invention this flexibility of the upper contact head with respect to the spindles can be achieved in such a manner that the tensioning nuts provided on the spindles cause a displacement of the upper contact head on the spindles by wayof semi-spherical intermediate members.

Further objects and advantageous details of the invention will become apparent from the following description of the embodiments of the invention illustrated in the accompanying drawings, in which:

Fig. 1 is an elevational view, partly in section, of an embodiment ofthe invention illustrating the melting apparatus; I

Fig. 2 is a different embodiment of the invention in which a tubular member is connected between the contact cross-heads and where a crucible is arranged for receiving the charge.- I

Like reference numerals in the drawings identify equivalent parts.

The contact assembly comprises upper andlower head members 1 and 2 which are suitably connected by way of movable current leads (not shown) to the secondary of atransformer. The head members 1 and 2 may be made of red brass or tombac and are adapted to receive the upper and lower carbon contacts 3 and 4. A receptacle such as a melting crucible 5 of graphite or carbon is received between heads 1 and 2 or contacts 3 and 4, respectively, as illustrated by the embodiment in accordance with Fig. l, and the charge is received in the crucible which is heated by the current flowing through heads 1, 2 and contacts 3, 4, thus causing the charge in the receptacle to, melt. In the embodiment in accordance with Fig. 1 an intermediate member. 6'is also placed between the contact .3 and crucible 5. i v

, The upper contact head is guided at both sides by spaced connecting devices including two spindles 7 and and 10 in which they are free to move'in axialdireotion. The lower. contact head2 is secured to the lowerends of the tubes 9 and 10 by means of the bolts 11 andnuts 12. ;The tubes 9 and 10 at their upper ends receive guiding sleeves 13' against the lower ends of which springs 14 are biased inside the tubes 9 and 10. The springs 14 are mounted upon the lower ends of spindles 7 and 8 in such a manner that-movement of the spindles '7 and 8, upwardly in axial direction is against the tension of springs 14 and thus tightens these springs. The movement of spindles 7 and 8 is efiected by means of nuts '15 which maybe operated bymanipulating means 16. If nuts 15 are tightened on the spindles 7 and 8, the contact head 1 including contact 3 and the intermediate member 6 are tightened against the crucible 5 and against the lower contact head 2 and contact 4, The tensioning of the upper contact head 1 against the crucible 5 is effected by elastic means because the contacthead 1 is enabled to yield upwardly against the effect of springs 14 within the tubular members 9 and 10. Thus, if the crucible 5 expands during the process of melting in its axial direction, the inherent tensions cannot attain a high force because the contact head 1 is capable of yielding upwardly. Thus, damaging of the crucible 5 as a result of these tensions is avoided.

In order to enable the contact head 1 to assume any desirable oblique position with respect to the axial direction of spindles 7 and 8 for the purpose of compensating for inaccuracies at the upper or lower transverse plane of the crucible 5, the nuts 15 present spherical surfaces at their lower ends 17. The nuts 15 with their spherical ends 17 are connected by means of shells 18 to guiding members 19 for the contact head 1, which guiding members are provided with central bores to loosely receive the spindles 7 and 8. As indicated in the drawing, the nuts 15 press against the guiding member 19 of the contact head 1 by means of spherical surfaces 17. Since the guiding members 19 are also of spherical conformation at their ends facing the nuts 15, the contact head 1 is enabled to adjust itself in a suitable manner obliquely to the axes'of the spindles 7 and 8, thereby compensating for any inaccuracy which at the contact planes with the crucible 5 could lead to local overheating or burn outs.

Fig. 2 corresponds substantially to the embodiment of Fig. 1, except that in this embodiment a carbon tube 20 is placed between the contacts 3 and 4- or contact heads -1 and 2, and a'special type of crucible 21 is arranged inside this carbon tube, which crucible may, for example, be made of'ceramic material having a'very high melting point- In all cases the upper contact head 1 or contact 3 is provided-with an aperture 22 which makes it possible to observe the charge from the outside or, as indicated in Fig; 2, permits also "removing the crucible"21 from the melting apparatus or replacing it inside of the apparatus. Moreover, the entire melting apparatus may be mounted on particularsupporting members (not shown) for tilting movement. V The apparatus in accordance with the invention is particularly suitable for laboratory purposes where small quantities 'of-silver,igold platinum, tungsten, or the like, or metal alloys 'must'be melted. It is, of course, also possibl'e'to use the principle in accordance with the invention for large'r charges of, for example, 100 kilograms. Having now described my invention with reference to the embodiments illustrated in the accompanying drawings, I do not wish to be limited thereto, but what I desire to protect by 'Letters Patent of the United States is set forth in the "appended claims.

,Iclaim': e

1. Apparatus for melting metals, metal alloys and the like, and other substances having a high melting point, said apparatus comprising an upper and a lower electrical con tact ofcarbon or the like} an electrically heated receptacle 7 presenting opposite flat end surfaces and mounted intermediate said contacts in the manner of are'sistor and engaging said contacts'with said flat end surfaces and mechanical means including upper andlowerhead members r'espectively' supporting said upper-and lower contacts against said end surfaces,- said upper head member having an aperture defined substantially centrally thereof, and spaced connecting devices including spring biasing means, said connecting devices extending laterally of said head members and having upper and lower ends secured to said upper and lower head members respectively and resiliently biasing said contacts in opposite directions toward each other andto w'ard said receptacle, said head members being provided with recesses and said contacts being received in said recesses at their ends remote from the ends of said receptacle, and said upper contact having an aperture generally in alignmentwith the aperture in said upper head member permitting access to said re: a t. .N. i 7

2. Apparatus for melting metals, metal alloys and the like, and other substances having a high melting point, said apparatus comprising an upper and a lower electrical contact of carbon or the like, an electrically heated receptacle in the form of a resistor of carbon or the like presenting opposite fiat end surfaces, said receptacle being mounted intermediate said contacts in the manner of a resistor and engaging said contacts with said flat end surfaces and mechanical means including upper and lower head members respectively supporting said upper and lowercontacts against said end surfaces, said upper head member having an aperture defined substantially centrally thereof, and spaced'connecting devices including spring biasing means, said connecting devices extending laterally of said head members and having upper and lower ends secured to said upper and lower head members respectively and resiliently biasing said contacts in opposite directions toward each other and toward said receptacle, said head members being provided with recesses and said contacts being received in said recesses at their ends remote from the ends of said receptacle, and said upper contact having an aperture generally in alignment with the aperture in said upper head member permitting access to said receptacle.

3. Apparatus for melting metals, metal alloys and the like, and other substances having a high melting point, said apparatus comprising an upper and a lower electrical contact of carbon or the like, an electrically heated receptacle in the form of a tube presenting opposite flat end surfaces, said receptacle being mounted intermediate said contacts .in the manner of a resistor and engaging said contacts with said flat end surfaces and mechanical means including upper and lower head members respectively supporting said upper and lower contacts against said end surfaces, said upper head member having an aperture defined substantially centrally thereof, and spaced connecting devices including spring biasing means, said connecting devicesextending laterally of said head members andhaving .upper and lower ends secured to said upper and lower head members respectively and resiliently biasing said contacts in opposite directions toward each other and toward said receptacle, said head members being provided with recesses and said contacts being received in said :recesses at their ends remote from theends of said receptacle, and said upper contact having an aperture generally in alignment withrthe aperture in. said upper head member permitting access to said receptacle. 4. Apparatus for melting metals, metal alloys and the like, and other substances having a high melting point, said apparatus comprising an upper and a lower electrical contact of carbon or thelikegan electrically heated rec'epta'cle in the form of a resistor of carbon or the like presenting opposite flat end surfaces, said receptacle being mounted intermediate said contacts in the manner of a resistor and engaging said contacts with said flat end surfaces and mechanical means including upper and lower head'members respectively supporting said upper and lower-contacts against said end surfaces, said upper head member having an aperture defined substantially'centrally thereof, and spaced connecting devices including spring biasing means, said connecting devices extending laterally i of'said head members and havingupper and lower ends secured to; said upper and lowerhead members respec'. tively and resiliently biasing said contacts in opposite diire'ctionstoward each other and toward said receptacle, said head :members being provided withreccsses and said-con.- tacts b'eing received in said recesses attheir ends re mote from the ends of said receptacle, and said upper contact having an aperture generallyiin alignment. with the "aperture in said upper head member permitting access to said'receptacle, said connecting devices comprising a pairfof'spindles," a pair of tubes, each supporting one said spindle with a biasing. spring'disposed intermediate each said spindle and said tube, one said head 'mmberbeing rigidly. secured at opposite ends to the lower ends of said tubes and the other said head member being slidingly 5 supfined at opposite ends on the upper ends of said References Cited in the file of this patent spin es in a manner to resilientl yield to the ressm'e from said receptacle, a head sugporting memb r being UNITED STATES PATENTS mounted on each said spindle, said upper head member 769,250 Conley Sept-6, 1904 being secured at each end to one said head supporting 5 932,986 Helberger Aug. 31, 1909 member, and a tightening nut being threadedly mounted 1,011,594 Dunham Dec. 12, 1911 on each said spindle, said head supporting members 1,430,858 Speirs Oct. 3,1922 and said tightening nuts having corresponding surfaces 2,304,311 Luce Dec. 8, 1942 of spherical conformation permitting oblique adjustment 2,434,826 Wubben Ian. 20, 1948 of said head relative to said spindles. 10 2,805,035 Coombs Sept. 31, 1957 

1. APPARATUS FOR MELTING METALS, METAL ALLOYS AND THE LIKE, AND OTHER SUBSTANCES HAVING A HIGH MELTING POINT, SAID APPARATUS COMPRISING AN UPPER AND A LOWER ELECTRICAL CONTACT OF CARBON OR THE LIKE, AN ELECTRICALLY HEATED RECEPTACLE PRESENTING OPPOSITE FLAT END SURFACES AND MOUNTED INTERMEDIATE SAID CONTACTS IN THE MANNER OF A RESISTOR AND ENGAGING SAID CONTACTS IN THE MANNER OF A RESISTOR AND ENCHANICAL MEANS INCLUDING UPPER AND LOWER HEAD MEMBERS RESPECTIVELY SUPPORTING SAID UPPER AND LOWER CONTACTS AGAINST SAID END SURFACES, SAID UPPER HEAD MEMBER HAVING AN APERTURE DEFINED SUBSTANTIALLY CENTRALLY THEREOF, AND SPACED CONNECTING DEVICES INCLUDING SPRING BIASING 